// Emacs style mode select	 -*- C++ -*-
//-----------------------------------------------------------------------------
//
// $Id:$
//
// Copyright (C) 1993-1996 by id Software, Inc.
//
// This source is available for distribution and/or modification
// only under the terms of the DOOM Source Code License as
// published by id Software. All rights reserved.
//
// The source is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
// for more details.
//
// $Log:$
//
// DESCRIPTION:
//		The actual span/column drawing functions.
//		Here find the main potential for optimization,
//		 e.g. inline assembly, different algorithms.
//
//-----------------------------------------------------------------------------


static const char
rcsid[] = "$Id: r_draw.c,v 1.4 1997/02/03 16:47:55 b1 Exp $";


#include "doomdef.h"

#include "i_system.h"
#include "z_zone.h"
#include "w_wad.h"

#include "r_local.h"

// Needs access to LFB (guess what).
#include "v_video.h"

// State.
#include "doomstat.h"


// ?
#define MAXWIDTH						1120
#define MAXHEIGHT						832

// status bar height at bottom of screen
#define SBARHEIGHT				32

//
// All drawing to the view buffer is accomplished in this file.
// The other refresh files only know about ccordinates,
//	not the architecture of the frame buffer.
// Conveniently, the frame buffer is a linear one,
//	and we need only the base address,
//	and the total size == width*height*depth/8.,
//


byte*			viewimage;
int				viewwidth;
int				scaledviewwidth;
int				viewheight;
int				viewwindowx;
int				viewwindowy;
byte*			ylookup[MAXHEIGHT];
int				columnofs[MAXWIDTH];

// Color tables for different players,
//	translate a limited part to another
//	(color ramps used for  suit colors).
//
byte			translations[3][256];




//
// R_DrawColumn
// Source is the top of the column to scale.
//
lighttable_t*			dc_colormap;
int						dc_x;
int						dc_yl;
int						dc_yh;
fixed_t					dc_iscale;
fixed_t					dc_texturemid;

// first pixel in a column (possibly virtual)
byte*					dc_source;

// just for profiling
int						dccount;

//
// A column is a vertical slice/span from a wall texture that,
//	given the DOOM style restrictions on the view orientation,
//	will always have constant z depth.
// Thus a special case loop for very fast rendering can
//	be used. It has also been used with Wolfenstein 3D.
//
void R_DrawColumn (void)
{
    int					count;
    byte*				dest;
    fixed_t				frac;
    fixed_t				fracstep;

    count = dc_yh - dc_yl;

    // Zero length, column does not exceed a pixel.
    if (count < 0)
        return;

#ifdef RANGECHECK
    if ((unsigned)dc_x >= SCREENWIDTH
            || dc_yl < 0
            || dc_yh >= SCREENHEIGHT)
        I_Error ("R_DrawColumn: %i to %i at %i", dc_yl, dc_yh, dc_x);
#endif

    // Framebuffer destination address.
    // Use ylookup LUT to avoid multiply with ScreenWidth.
    // Use columnofs LUT for subwindows?
    dest = ylookup[dc_yl] + columnofs[dc_x];

    // Determine scaling,
    //	which is the only mapping to be done.
    fracstep = dc_iscale;
    frac = dc_texturemid + (dc_yl-centery)*fracstep;

    // Inner loop that does the actual texture mapping,
    //	e.g. a DDA-lile scaling.
    // This is as fast as it gets.
    do
    {
        // Re-map color indices from wall texture column
        //	using a lighting/special effects LUT.
        *dest = dc_colormap[dc_source[(frac>>FRACBITS)&127]];

        dest += SCREENWIDTH;
        frac += fracstep;

    } while (count--);
}



// UNUSED.
// Loop unrolled.
#if 0
void R_DrawColumn (void)
{
    int					count;
    byte*				source;
    byte*				dest;
    byte*				colormap;

    unsigned			frac;
    unsigned			fracstep;
    unsigned			fracstep2;
    unsigned			fracstep3;
    unsigned			fracstep4;

    count = dc_yh - dc_yl + 1;

    source = dc_source;
    colormap = dc_colormap;
    dest = ylookup[dc_yl] + columnofs[dc_x];

    fracstep = dc_iscale<<9;
    frac = (dc_texturemid + (dc_yl-centery)*dc_iscale)<<9;

    fracstep2 = fracstep+fracstep;
    fracstep3 = fracstep2+fracstep;
    fracstep4 = fracstep3+fracstep;

    while (count >= 8)
    {
        dest[0] = colormap[source[frac>>25]];
        dest[SCREENWIDTH] = colormap[source[(frac+fracstep)>>25]];
        dest[SCREENWIDTH*2] = colormap[source[(frac+fracstep2)>>25]];
        dest[SCREENWIDTH*3] = colormap[source[(frac+fracstep3)>>25]];

        frac += fracstep4;

        dest[SCREENWIDTH*4] = colormap[source[frac>>25]];
        dest[SCREENWIDTH*5] = colormap[source[(frac+fracstep)>>25]];
        dest[SCREENWIDTH*6] = colormap[source[(frac+fracstep2)>>25]];
        dest[SCREENWIDTH*7] = colormap[source[(frac+fracstep3)>>25]];

        frac += fracstep4;
        dest += SCREENWIDTH*8;
        count -= 8;
    }

    while (count > 0)
    {
        *dest = colormap[source[frac>>25]];
        dest += SCREENWIDTH;
        frac += fracstep;
        count--;
    }
}
#endif


void R_DrawColumnLow (void)
{
    int					count;
    byte*				dest;
    byte*				dest2;
    fixed_t				frac;
    fixed_t				fracstep;

    count = dc_yh - dc_yl;

    // Zero length.
    if (count < 0)
        return;

#ifdef RANGECHECK
    if ((unsigned)dc_x >= SCREENWIDTH
            || dc_yl < 0
            || dc_yh >= SCREENHEIGHT)
    {

        I_Error ("R_DrawColumnLow: %i to %i at %i\n", dc_yl, dc_yh, dc_x);
    }
    //	dccount++;
#endif
    // Blocky mode, need to multiply by 2.
    dc_x <<= 1;

    dest = ylookup[dc_yl] + columnofs[dc_x];
    dest2 = ylookup[dc_yl] + columnofs[dc_x+1];

    fracstep = dc_iscale;
    frac = dc_texturemid + (dc_yl-centery)*fracstep;

    do
    {
        // Hack. Does not work corretly.
        *dest2 = *dest = dc_colormap[dc_source[(frac>>FRACBITS)&127]];
        dest += SCREENWIDTH;
        dest2 += SCREENWIDTH;
        frac += fracstep;

    } while (count--);
}


//
// Spectre/Invisibility.
//
#define FUZZTABLE				50
#define FUZZOFF (SCREENWIDTH)


int		fuzzoffset[FUZZTABLE] =
{
    FUZZOFF,-FUZZOFF,FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,
    FUZZOFF,FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,
    FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,-FUZZOFF,-FUZZOFF,-FUZZOFF,
    FUZZOFF,-FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,
    FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,-FUZZOFF,FUZZOFF,
    FUZZOFF,-FUZZOFF,-FUZZOFF,-FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,
    FUZZOFF,FUZZOFF,-FUZZOFF,FUZZOFF,FUZZOFF,-FUZZOFF,FUZZOFF
};

int		fuzzpos = 0;


//
// Framebuffer postprocessing.
// Creates a fuzzy image by copying pixels
//	from adjacent ones to left and right.
// Used with an all black colormap, this
//	could create the SHADOW effect,
//	i.e. spectres and invisible players.
//
void R_DrawFuzzColumn (void)
{
    int					count;
    byte*				dest;
    fixed_t				frac;
    fixed_t				fracstep;

    // Adjust borders. Low...
    if (!dc_yl)
        dc_yl = 1;

    // .. and high.
    if (dc_yh == viewheight-1)
        dc_yh = viewheight - 2;

    count = dc_yh - dc_yl;

    // Zero length.
    if (count < 0)
        return;


#ifdef RANGECHECK
    if ((unsigned)dc_x >= SCREENWIDTH
            || dc_yl < 0 || dc_yh >= SCREENHEIGHT)
    {
        I_Error ("R_DrawFuzzColumn: %i to %i at %i",
                 dc_yl, dc_yh, dc_x);
    }
#endif


    // Keep till detailshift bug in blocky mode fixed,
    //	or blocky mode removed.
    /* WATCOM code
    if (detailshift)
    {
    	if (dc_x & 1)
    	{
    		outpw (GC_INDEX,GC_READMAP+(2<<8) );
    		outp (SC_INDEX+1,12);
    	}
    	else
    	{
    		outpw (GC_INDEX,GC_READMAP);
    		outp (SC_INDEX+1,3);
    	}
    	dest = destview + dc_yl*80 + (dc_x>>1);
    }
    else
    {
    	outpw (GC_INDEX,GC_READMAP+((dc_x&3)<<8) );
    	outp (SC_INDEX+1,1<<(dc_x&3));
    	dest = destview + dc_yl*80 + (dc_x>>2);
    }*/


    // Does not work with blocky mode.
    dest = ylookup[dc_yl] + columnofs[dc_x];

    // Looks familiar.
    fracstep = dc_iscale;
    frac = dc_texturemid + (dc_yl-centery)*fracstep;

    // Looks like an attempt at dithering,
    //	using the colormap #6 (of 0-31, a bit
    //	brighter than average).
    do
    {
        // Lookup framebuffer, and retrieve
        //	a pixel that is either one column
        //	left or right of the current one.
        // Add index from colormap to index.
        *dest = colormaps[6*256+dest[fuzzoffset[fuzzpos]]];

        // Clamp table lookup index.
        if (++fuzzpos == FUZZTABLE)
            fuzzpos = 0;

        dest += SCREENWIDTH;

        frac += fracstep;
    } while (count--);
}




//
// R_DrawTranslatedColumn
// Used to draw player sprites
//	with the green colorramp mapped to others.
// Could be used with different translation
//	tables, e.g. the lighter colored version
//	of the BaronOfHell, the HellKnight, uses
//	identical sprites, kinda brightened up.
//
byte*	dc_translation;
byte*	translationtables;

void R_DrawTranslatedColumn (void)
{
    int					count;
    byte*				dest;
    fixed_t				frac;
    fixed_t				fracstep;

    count = dc_yh - dc_yl;
    if (count < 0)
        return;

#ifdef RANGECHECK
    if ((unsigned)dc_x >= SCREENWIDTH
            || dc_yl < 0
            || dc_yh >= SCREENHEIGHT)
    {
        I_Error ( "R_DrawColumn: %i to %i at %i",
                  dc_yl, dc_yh, dc_x);
    }

#endif



    // WATCOM VGA specific.
    /* Keep for fixing.
    if (detailshift)
    {
    	if (dc_x & 1)
    		outp (SC_INDEX+1,12);
    	else
    		outp (SC_INDEX+1,3);

    	dest = destview + dc_yl*80 + (dc_x>>1);
    }
    else
    {
    	outp (SC_INDEX+1,1<<(dc_x&3));

    	dest = destview + dc_yl*80 + (dc_x>>2);
    }*/


    // FIXME. As above.
    dest = ylookup[dc_yl] + columnofs[dc_x];

    // Looks familiar.
    fracstep = dc_iscale;
    frac = dc_texturemid + (dc_yl-centery)*fracstep;

    // Here we do an additional index re-mapping.
    do
    {
        // Translation tables are used
        //	to map certain colorramps to other ones,
        //	used with PLAY sprites.
        // Thus the "green" ramp of the player 0 sprite
        //	is mapped to gray, red, black/indigo.
        *dest = dc_colormap[dc_translation[dc_source[frac>>FRACBITS]]];
        dest += SCREENWIDTH;

        frac += fracstep;
    } while (count--);
}




//
// R_InitTranslationTables
// Creates the translation tables to map
//	the green color ramp to gray, brown, red.
// Assumes a given structure of the PLAYPAL.
// Could be read from a lump instead.
//
void R_InitTranslationTables (void)
{
    int			i;

    translationtables = Z_Malloc (256*3+255, PU_STATIC, 0);
    translationtables = (byte *)(( (int)translationtables + 255 )& ~255);

    // translate just the 16 green colors
    for (i=0 ; i<256 ; i++)
    {
        if (i >= 0x70 && i<= 0x7f)
        {
            // map green ramp to gray, brown, red
            translationtables[i] = 0x60 + (i&0xf);
            translationtables [i+256] = 0x40 + (i&0xf);
            translationtables [i+512] = 0x20 + (i&0xf);
        }
        else
        {
            // Keep all other colors as is.
            translationtables[i] = translationtables[i+256]
                                   = translationtables[i+512] = i;
        }
    }
}




//
// R_DrawSpan
// With DOOM style restrictions on view orientation,
//	the floors and ceilings consist of horizontal slices
//	or spans with constant z depth.
// However, rotation around the world z axis is possible,
//	thus this mapping, while simpler and faster than
//	perspective correct texture mapping, has to traverse
//	the texture at an angle in all but a few cases.
// In consequence, flats are not stored by column (like walls),
//	and the inner loop has to step in texture space u and v.
//
int						ds_y;
int						ds_x1;
int						ds_x2;

lighttable_t*			ds_colormap;

fixed_t					ds_xfrac;
fixed_t					ds_yfrac;
fixed_t					ds_xstep;
fixed_t					ds_ystep;

// start of a 64*64 tile image
byte*					ds_source;

// just for profiling
int						dscount;


//
// Draws the actual span.
void R_DrawSpan (void)
{
    fixed_t				xfrac;
    fixed_t				yfrac;
    byte*				dest;
    int					count;
    int					spot;

#ifdef RANGECHECK
    if (ds_x2 < ds_x1
            || ds_x1<0
            || ds_x2>=SCREENWIDTH
            || (unsigned)ds_y>SCREENHEIGHT)
    {
        I_Error( "R_DrawSpan: %i to %i at %i",
                 ds_x1,ds_x2,ds_y);
    }
//		dscount++;
#endif

    xfrac = ds_xfrac;
    yfrac = ds_yfrac;

    dest = ylookup[ds_y] + columnofs[ds_x1];

    // We do not check for zero spans here?
    count = ds_x2 - ds_x1;

    do
    {
        // Current texture index in u,v.
        spot = ((yfrac>>(16-6))&(63*64)) + ((xfrac>>16)&63);

        // Lookup pixel from flat texture tile,
        //	re-index using light/colormap.
        *dest++ = ds_colormap[ds_source[spot]];

        // Next step in u,v.
        xfrac += ds_xstep;
        yfrac += ds_ystep;

    } while (count--);
}



// UNUSED.
// Loop unrolled by 4.
#if 0
void R_DrawSpan (void)
{
    unsigned	position, step;

    byte*		source;
    byte*		colormap;
    byte*		dest;

    unsigned	count;
    usingned	spot;
    unsigned	value;
    unsigned	temp;
    unsigned	xtemp;
    unsigned	ytemp;

    position = ((ds_xfrac<<10)&0xffff0000) | ((ds_yfrac>>6)&0xffff);
    step = ((ds_xstep<<10)&0xffff0000) | ((ds_ystep>>6)&0xffff);

    source = ds_source;
    colormap = ds_colormap;
    dest = ylookup[ds_y] + columnofs[ds_x1];
    count = ds_x2 - ds_x1 + 1;

    while (count >= 4)
    {
        ytemp = position>>4;
        ytemp = ytemp & 4032;
        xtemp = position>>26;
        spot = xtemp | ytemp;
        position += step;
        dest[0] = colormap[source[spot]];

        ytemp = position>>4;
        ytemp = ytemp & 4032;
        xtemp = position>>26;
        spot = xtemp | ytemp;
        position += step;
        dest[1] = colormap[source[spot]];

        ytemp = position>>4;
        ytemp = ytemp & 4032;
        xtemp = position>>26;
        spot = xtemp | ytemp;
        position += step;
        dest[2] = colormap[source[spot]];

        ytemp = position>>4;
        ytemp = ytemp & 4032;
        xtemp = position>>26;
        spot = xtemp | ytemp;
        position += step;
        dest[3] = colormap[source[spot]];

        count -= 4;
        dest += 4;
    }
    while (count > 0)
    {
        ytemp = position>>4;
        ytemp = ytemp & 4032;
        xtemp = position>>26;
        spot = xtemp | ytemp;
        position += step;
        *dest++ = colormap[source[spot]];
        count--;
    }
}
#endif


//
// Again..
//
void R_DrawSpanLow (void)
{
    fixed_t				xfrac;
    fixed_t				yfrac;
    byte*				dest;
    int					count;
    int					spot;

#ifdef RANGECHECK
    if (ds_x2 < ds_x1
            || ds_x1<0
            || ds_x2>=SCREENWIDTH
            || (unsigned)ds_y>SCREENHEIGHT)
    {
        I_Error( "R_DrawSpan: %i to %i at %i",
                 ds_x1,ds_x2,ds_y);
    }
//		dscount++;
#endif

    xfrac = ds_xfrac;
    yfrac = ds_yfrac;

    // Blocky mode, need to multiply by 2.
    ds_x1 <<= 1;
    ds_x2 <<= 1;

    dest = ylookup[ds_y] + columnofs[ds_x1];


    count = ds_x2 - ds_x1;
    do
    {
        spot = ((yfrac>>(16-6))&(63*64)) + ((xfrac>>16)&63);
        // Lowres/blocky mode does it twice,
        //	while scale is adjusted appropriately.
        *dest++ = ds_colormap[ds_source[spot]];
        *dest++ = ds_colormap[ds_source[spot]];

        xfrac += ds_xstep;
        yfrac += ds_ystep;

    } while (count--);
}

//
// R_InitBuffer
// Creats lookup tables that avoid
//	multiplies and other hazzles
//	for getting the framebuffer address
//	of a pixel to draw.
//
void
R_InitBuffer
( int			width,
  int			height )
{
    int			i;

    // Handle resize,
    //	e.g. smaller view windows
    //	with border and/or status bar.
    viewwindowx = (SCREENWIDTH-width) >> 1;

    // Column offset. For windows.
    for (i=0 ; i<width ; i++)
        columnofs[i] = viewwindowx + i;

    // Samw with base row offset.
    if (width == SCREENWIDTH)
        viewwindowy = 0;
    else
        viewwindowy = (SCREENHEIGHT-SBARHEIGHT-height) >> 1;

    // Preclaculate all row offsets.
    for (i=0 ; i<height ; i++)
        ylookup[i] = screens[0] + (i+viewwindowy)*SCREENWIDTH;
}




//
// R_FillBackScreen
// Fills the back screen with a pattern
//	for variable screen sizes
// Also draws a beveled edge.
//
void R_FillBackScreen (void)
{
    byte*		src;
    byte*		dest;
    int			x;
    int			y;
    patch_t*	patch;

    // DOOM border patch.
    char		name1[] = "FLOOR7_2";

    // DOOM II border patch.
    char		name2[] = "GRNROCK";

    char*		name;

    if (scaledviewwidth == 320)
        return;

    if ( gamemode == commercial)
        name = name2;
    else
        name = name1;

    src = W_CacheLumpName (name, PU_CACHE);
    dest = screens[1];

    for (y=0 ; y<SCREENHEIGHT-SBARHEIGHT ; y++)
    {
        for (x=0 ; x<SCREENWIDTH/64 ; x++)
        {
            memcpy (dest, src+((y&63)<<6), 64);
            dest += 64;
        }

        if (SCREENWIDTH&63)
        {
            memcpy (dest, src+((y&63)<<6), SCREENWIDTH&63);
            dest += (SCREENWIDTH&63);
        }
    }

    patch = W_CacheLumpName ("brdr_t",PU_CACHE);

    for (x=0 ; x<scaledviewwidth ; x+=8)
        V_DrawPatch (viewwindowx+x,viewwindowy-8,1,patch);
    patch = W_CacheLumpName ("brdr_b",PU_CACHE);

    for (x=0 ; x<scaledviewwidth ; x+=8)
        V_DrawPatch (viewwindowx+x,viewwindowy+viewheight,1,patch);
    patch = W_CacheLumpName ("brdr_l",PU_CACHE);

    for (y=0 ; y<viewheight ; y+=8)
        V_DrawPatch (viewwindowx-8,viewwindowy+y,1,patch);
    patch = W_CacheLumpName ("brdr_r",PU_CACHE);

    for (y=0 ; y<viewheight ; y+=8)
        V_DrawPatch (viewwindowx+scaledviewwidth,viewwindowy+y,1,patch);


    // Draw beveled edge.
    V_DrawPatch (viewwindowx-8,
                 viewwindowy-8,
                 1,
                 W_CacheLumpName ("brdr_tl",PU_CACHE));

    V_DrawPatch (viewwindowx+scaledviewwidth,
                 viewwindowy-8,
                 1,
                 W_CacheLumpName ("brdr_tr",PU_CACHE));

    V_DrawPatch (viewwindowx-8,
                 viewwindowy+viewheight,
                 1,
                 W_CacheLumpName ("brdr_bl",PU_CACHE));

    V_DrawPatch (viewwindowx+scaledviewwidth,
                 viewwindowy+viewheight,
                 1,
                 W_CacheLumpName ("brdr_br",PU_CACHE));
}


//
// Copy a screen buffer.
//
void
R_VideoErase
( unsigned		ofs,
  int			count )
{
    // LFB copy.
    // This might not be a good idea if memcpy
    //  is not optiomal, e.g. byte by byte on
    //  a 32bit CPU, as GNU GCC/Linux libc did
    //  at one point.
    memcpy (screens[0]+ofs, screens[1]+ofs, count);
}


//
// R_DrawViewBorder
// Draws the border around the view
//	for different size windows?
//
void
V_MarkRect
( int			x,
  int			y,
  int			width,
  int			height );

void R_DrawViewBorder (void)
{
    int			top;
    int			side;
    int			ofs;
    int			i;

    if (scaledviewwidth == SCREENWIDTH)
        return;

    top = ((SCREENHEIGHT-SBARHEIGHT)-viewheight)/2;
    side = (SCREENWIDTH-scaledviewwidth)/2;

    // copy top and one line of left side
    R_VideoErase (0, top*SCREENWIDTH+side);

    // copy one line of right side and bottom
    ofs = (viewheight+top)*SCREENWIDTH-side;
    R_VideoErase (ofs, top*SCREENWIDTH+side);

    // copy sides using wraparound
    ofs = top*SCREENWIDTH + SCREENWIDTH-side;
    side <<= 1;

    for (i=1 ; i<viewheight ; i++)
    {
        R_VideoErase (ofs, side);
        ofs += SCREENWIDTH;
    }

    // ?
    V_MarkRect (0,0,SCREENWIDTH, SCREENHEIGHT-SBARHEIGHT);
}


